Title page for etd-0714117-124155


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URN etd-0714117-124155
Author Shih-Chieh Hung
Author's Email Address ro26873160@hotmail.com.tw
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Department Materials and Optoelectronic Science
Year 2016
Semester 2
Degree Master
Type of Document
Language zh-TW.Big5 Chinese
Title A Simulation study of an ultra-thin Si solar cell with CuInSe2 as bottom absorption layer
Date of Defense 2017-07-25
Page Count 98
Keyword
  • 2D semiconducting material (InSe)
  • Van der Waals epitaxy
  • CuInSe2
  • PC-1D device simulation tool for solar cells
  • Ultra-thin Si homojunction
  • Abstract The cost analysis of a crystalline Si solar cell indicates a considerable cost percentage belonging to the Si wafer. The advantages to use ultrathin Si wafers (5 ~ 50 μm in thickness) not only cut down the material cost but also extend its application on BIPV due to the flexibility of final product. A reduction in the wafer thickness may cause a significant loss of light absorption in Si. In this work, an efficient light absorber of CuInSe2 (CIS) with an optical coefficient as high as 10∧5 /cm is attached to the bottom of a Si homojunction to form a novel device structure of n-Si/p-Si/p-CIS. We perform the device simulation study by using PC-1D simulation tool along with the experimental data of material parameters acquired from the literature survey. Furthermore, Taguchi method has been applied to help optimizing the device performance. Since a large lattice mismatch between Si and CIS causes high surface recombination velocity of 4.79x10∧5 cm/s at the interface, an energy conversion efficiency of 18.9% (Voc=0.637V, Isc=33.5mA, FF=83.8%) is obtained. Modification of interfacial structure through the incorporation of a hydrogenated amorphous Si or Ge film at the Si/CIS interface has been proposed but the improvement in the energy conversion efficiency limited to only about 2%. It is attributed to the inferior properties of polycrystalline CIS as compared with those of single-crystalline CIS. Another way proposed for interface modification is the use of Van der Waals Epitaxy, i.e. a thin layer of 2D material such as InSe is inserted between Si and CIS in order to prohibit the formation of misfit dislocations at the interface. There exist the discontinuity of conduction band and valence band with different values at the Si/CIS interface, which in turn may separate the electrons and holes generated in CIS after light absorption. This leads to a tandem-cell behavior in our device. With a proper adjustment of device parameters, a device structure of n-Si(100nm)/p-Si(5μm)/p-InSe(20nm)/p-CIS(1700nm) may reach an energy conversion efficiency of 32.5% (Voc=0.781V, Isc=50.9mA, FF=81.8%).
    Advisory Committee
  • Houng, Mau-Phon - chair
  • Wei-Hung Su - co-chair
  • Bae-Heng Tseng - advisor
  • Files
  • etd-0714117-124155.pdf
  • indicate access worldwide
    Date of Submission 2017-08-14

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